Planar sudden symmetric expansion flows and bifurcation phenomena of purely viscous shear-thinning fluids

Abstract

The goal of a present study is to investigate the effects of the generalized Newtonian fluids on the threshold of the transition from flow symmetry to its asymmetry for the flow through a 1:3 planar sudden expansion. We consider purely viscous shear-thinning fluids covering a range of the index n of Power law model n = 0.6 , 0.8 and compare them with the Newtonian fluid ( n = 1.0 ). Sudden expansion fluid flow is studied numerically by solving the two-dimensional momentum equations along with the continuity equation and the Power law rheological model. We report a systematic results in a range of generalized Reynolds number 10 ≤ R e g e n ≤ 150 with a focus on its critical value. The subsequent effects are investigated by means of a different flow parameters, i.e. generalized Reynolds number ( R e g e n ), modified Reynolds number ( R e m o d ) and the Reynolds number defined in accordance with the inlet wall viscosity ( R e w a l l ). Results indicate that the shear-thinning viscous behaviour increases the onset of bifurcation phenomena and the critical value of Reynolds number.